The present invention relates generally to passenger restraint systems and, more particularly, to safety belt retractors of the type used in vehicular seating applications.
Virtually all motor vehicles are now equipped with safety belt restraint systems for physically restraining the seat occupants when the vehicle is subjected to a high rate of deceleration which may occur, for example, during a motor vehicle collision. Traditionally, safety belt restraint systems include one of more rotary-type safety belt retractors which function to normally permit the belt webbing to be controllably withdrawn and retracted from a spring-biased spool assembly. It is also known to provide such rotary-type belt retractors with a selectively engageable locking mechanism for lockingly engaging the spool assembly in response to the occurrence of a predetermined event (i.e., latching of the belt buckle, vehicular deceleration forces above a maximum level, etc.), whereby subsequent withdrawal of belt webbing is prevented for restraining the vehicle occupant. As an additional comfort feature, some safety belt retractors are also equipped with a "tension" relief mechanism which functions to introduce a limited amount of "slack" into the belt webbing. In this manner, the spring-biased spool assembly is prevented from exerting a continuous retractive force on the belt webbing which tends to be uncomfortable and annoying to the seat occupant.
While conventional safety belt restraint systems are well-suited for restraining adult passengers, it is a common practice to use an auxiliary child seat having a belt-type harness restraint for children under a given age and weight. As is known, the child seat is placed on top of the vehicle seat and is secured thereto using the existing vehicular safety belt restraint system. It is also known to incorporate the aforementioned rotary-type belt retractor into the child seat for preventing withdrawal of the harness restraint once the child is fastened therein. An example of such a locking arrangement for an auxiliary child seat is disclosed in U.S. Pat. No. 4,720,148.
In an effort to minimize the inconvenience associated with installing and/or stowing auxiliary child seats, some motor vehicles are now available with seating arrangements having a "sold-out" or integral child seat which is incorporated into the backrest of an otherwise conventional seat. Typically, such seating arrangements are adapted to normally accommodate an adult in a seated position when the integral child seat is "concealed" within the backrest. When needed, the integral child seat can be easily deployed to expose a belt-type harness restraint that is provided for releasably retaining the child therein. To provide means for adjusting the amount of tension exerted on the child, it is known to incorporate a "tightening" mechanism into the harness restraint of the integral child seat. One commercially-available integral child seat employs a cinch-type belt tightening arrangement that can be manually-operated for adjusting the circuitous length of the harness restraint.
As an alternative to conventional cinch-type belt tightening devices, it is highly desireable to provide a "automatic" tightening mechanism which is operable to exert a retractive force on the harness restraint while preventing withdrawal thereof in response to buckling the child into the harness restraint. Such an automatic tightening mechanism offers greater convenience to the user, since no separate adjustment operations are required. Thus, it has been proposed to incorporate a conventional rotary-type belt retractor having a selectively engageable locking mechanism into an integral child seat for use as an automatic tightening mechanism. Unfortunately, in view of the need to provide comfort to adult seat occupants and preserve the overall cosmetic appearance of the seating arrangement when the integral child seat is in the concealed position, the available space for mounting such a conventional rotary-type belt retractor is severely limited.
In view of the above, the need exists to develop alternative safety belt retractors which can be efficiently packaged in a compact environment and which can be provided in either manually-operable or automatic versions.